The fundamental relationships between information theory and estimation theory attract the attentions of many researchers in recent
years [1]}, [2]}, [3]}, [4]}, [5]}, [6]}, [7]}, [8]}. One of the major successful results in this regard is the describing the relations between mutual information and Minimum Mean Square Error (MMSE), i.e. I-MMSE, which gives a new insight into the above theories [9]}, [10]}, [11]}, [12]}, [13]}, [14]}. In all the above studies the derivative of information measures such as entropy and mutual information are considered.
